Microseismic data acquisition and processing has been used for some time to image faults in the subsurface of the earth. More recently, microseismic techniques have been used to monitor fractures occurring in the subsurface of the earth as a result of hydraulic fracturing. When hydraulic fracturing fluid is pumped at high pressure into a well bore, the surrounding geologic layers fracture, and emit energy in the form of seismic waves. This seismic energy can be mapped to show the location, the extent and the effectiveness of the hydraulic fracturing operation.
In conventional seismic surveying, a controlled source such as explosives or a vibratory source is used. These sources have well known characteristics. In microseismic surveying, the source of the energy is a fracture in the subsurface of the earth, which has directional characteristics, and does not emit energy equally in all directions. Microseismic data processing uses many techniques from conventional seismic surveying, and many new techniques have been developed specifically for processing microseismic data. Most microseismic processing does not take into account the characteristics of the source of the energy, and therefore produces less than optimal results. What is required are improved techniques for processing microseismic data.